Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a front view of a display screen or portion thereof with transitional graphical user interface showing the first image of a sequence according to our new design;

FIG. 2 is a second image thereof;

FIG. 3 is a third image thereof;

FIG. 4 is a front view of a display screen or portion thereof with transitional graphical user interface showing the first image of a sequence according to a second embodiment of our design;

FIG. 5 is a second image thereof; and,

FIG. 6 is a third image thereof.

The appearance of the transitional image sequentially transitions between the images shown in the respective embodiments of FIGS. 1-3 and FIGS. 4-6. The process or period in which one image transitions to another image forms no part of the claimed design.

The dot-dash broken line perimeter illustrates a display screen or portion thereof and forms no part of the claimed design.

The portions shown in a pattern of stipple tone illustrate areas of contrasting appearance. 

CLAIM The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 